Climate-Driven Range Shifts of an Endangered Tree Species: A MaxEnt-Based Analysis of Cercidiphyllum japonicum in China

The relict tree Cercidiphyllum japonicum, a Tertiary paleoendemic with high ecological and timber value, exhibits strong preferences for warm-cool humid climates and acidic soils. Using MaxEnt and ArcGIS, we modeled its distribution under current and future climates (SSP scenarios). Current high-suitability areas (>0.6 probability) are concentrated in the Sichuan Basin and Yellow-Yangtze transition zones. By 2050, northwestward expansions (14.32–18.76% area increase) and eastward dispersal to Central China are projected under SSP1-2.6 and SSP5-8.5. However, by 2090, habitat losses exceed 22% under SSP5-8.5. Key drivers include minimum coldest-month temperature (bio6, 38.7%), annual precipitation (bio12, 29.1%), and temperature range (bio7, 18.5%), with precipitation seasonality and thermal extremes becoming critical future constraints. Conservation priorities include: (1) protecting refugia in the Daba-Wushan mountains, (2) assisted migration to northwestern high-latitudes, and (3) microclimate preservation. This study provides a framework for evidence-based conservation of paleoendemics under climate change.